Idea for 120mm CPU cooler drwing air from OUTSIDE

[Hughhefner]

Hello everyone, I just received my Newest batch of NIUHB 1800's, DLT3C and they are FINE chips indeed.

Came across the idea of what to do with my 120mm by 38mm SUNON High outout fan from my old Vapochill.

I just installed a Thermaltake Duct mod with my current TTSM2 hoping to achieve lower temps with the HOT SPOT gone. All is well but the temps when 1.75V at 2426mhz are still TOO high for me at 129F.

So here is the idea.

My cooler is the new Thermalright SLK900A clip on.
I'm going to build a TOWER of perhaps 3 to 4 80mm fan case housings "Fans and fins removed", then on top attach a 120mm to 80mm Neck down adapter. On tops of course will go the High output Sunon. The height the the tower and the fans will extend to or just past the side opening of my case. The case has a clear plastic panel.

I will cut an opening in the side panel enabling the 120mm fan to draw its air DIRECTLY from outside the case.

The case is a mid tower and also has 4 80mm intake fans in the lower front, and 2 80mm exhaust fans in the rear.

The 120mm Sunon should have more than enough power to pust the air the extra distance and still give great airflow. I'm going to check the specs but its a 12 volt fan and is rated at 6.8 watts
Over 100CFM at 3000RPM

what do you guys think

[CrashOveride]

Sounds like a great idea (and oftentimes has worked) but I think it would be better to use a cup or something like that to drop down so it can be a more spread out transition to cut down on backpressure.

[gungeek]

Pulling cool air straight to the cpu heatsink is a good idea. I did that to my computer last night. I cut an 80mm hole in the case side over the cpu. I used a piece of thin, rolled-up cardboard to make a duct between the heatsink fan and the hole in the side. It dropped my temps from 51 to 46C. I don't have nearly the case airflow you have, so your results might not be as dramatic.

One concern is that you seem to have much more blowing in than out of the case. That pressure difference might reduce the effectiveness of your duct since it's having to push air into higher than normal pressure. It would be worth attempting to pulling air up through the heatsink and exhausting it via a duct, that would take advantage of the pressurized case, maybe:)

I'm not exactly sure how you would mount the 120mm fan tower. If you were thinking of attaching it directly to the heatsink and cpu socket with no other support, that would be alot of side stress on the retaining clips of the heatsink and whatever is holding the heatsink to the cpu. A good jolt could break a mount somewhere. Mounting it to the case side could make opening the case a challenge.

Before cutting any holes, use cardboard to mock-up what you're planning. Make sure it is worth the effort.

Like CrashOveride said, if you do have to reduce the 120mm fan down to 80mm, use a tapered cup or something that gradually forces the air together. Quick size changes do bad things for airflow.

I would just mount the largest fan reasonable directly to the heatsink, then run a duct to the side of the case. It's quicker, easier and much less likely to break something if the computer gets a jolt.

Let us know how it works out!

[Hughhefner]

Thanks for the comments, I forgot to add that I have a Dual fan Antec truepower 550 and a PCI slot fan also blowing out so the issue of pressure shouldn't be a problem,

Having the "tunnel duct" over the fan sounds much easier to do.

[gungeek]

Originally posted by Hughhefner
Having the "tunnel duct" over the fan sounds much easier to do.

I forgot to mention one thing about the side duct, it will make your computer louder especially on the duct side. I suspect noise isn't a huge issue considering all of the other fans but thought you should be aware of it. Blocking or taping over side holes is a standard thing for the "quiet PC" crowd, but the ultimate overclock isn't their goal either.

[CrashOveride]

Originally posted by gungeek


I forgot to mention one thing about the side duct, it will make your computer louder especially on the duct side. I suspect noise isn't a huge issue considering all of the other fans but thought you should be aware of it. Blocking or taping over side holes is a standard thing for the "quiet PC" crowd, but the ultimate overclock isn't their goal either.

Not if your CPU fan isn't any louder than your other, case, fans.

[extremecorvette]

Soulds go, post pictures if you do it. I have a 120 on my CPU

[gungeek]

Originally posted by CrashOveride
Not if your CPU fan isn't any louder than your other, case, fans.

You're correct. I forgot about the diffences between my cpu fan (74mm TMD at 5500RPM) and case fans (80mm at 2200-2500RPM). The duct does provide a very nice sound tube to the outside. This is a good reason to test using cardboard before cutting metal.

[Cool Frank]

Has anynone experimented on a ducting system where the air is pulled from the CPU heat sink and expelled out? Anybody with a 120mm fan with a ducting mod to attach to the CPU heat sink?

[Fast420A]

My dad's old gateway had a 120 mm hole in the side and the Slot A processor had a big heatsink on it and this special duct that held the 120mm fan against the hole in the side and over top of the big heatsink and NB passive sink. No on board temps but the temp probe I have shows 108 F under a folding load on the surface of the sink against the chip. It works fairly well with the crappy aluminum sink so a copper one would probably work pretty good. I would try using 120mm to 92mm adapters to keep the airflow faster than going down to 80mm would.

[Hughhefner]

So far all I can do is mount the huge sunon to my SLK900 by drilling mounting holes in the fan so the clips can grab.

I tried all TALL duct made of 80mm case fan housings but the weight just began to bend the heatsink and motherboard AWAY from the processor, NOT GOOD.

The fan works REALLY well pushing Around 100CFM while being MUCH quieter than my TT sm2.

Just going to work on a duct to draw the air later in the week, I
'll keep youposted, gotta go watch the CUBS!!!!

[ChazFx]

To save doing somthing as drastic as cutting a hole in the side of your case, or even just to make sure its gonna work.

Make a new case side out of some fairly rgid cardboard. If you get everything right, this peice of cardbaord can be your new permanent case side, or will make a template to make sure you get the hole right